Many types of surgical procedures involve insertion of some type of device into human tissue. For example, U.S. Pat. No. 5,674,184 (Hassler, Jr.) describes, in general terms, endoscopic surgery within body cavities, organs and joints. The patent is directed to a surgical cutting tool or trocar having a cannula for inserting an obdurator into tissue to be cut. The obdurator has a chisel-shaped, solid, optically-clear tip and guidance of the tip is by an endoscope. The tip has side-by-side electrodes (used for tissue cutting) connected to wires brought out via grooves in the outer wall of the tube.
U.S. Pat. No. 5,458,606 (Cohen et al.) generally describes a procedure for relieving hydrocephalus, otherwise known as water on the brain. The disclosed neuro endoscope is inserted into the cranial cavity. Such endoscope uses a stainless steel hollow tube (a "hypotube" as the patent calls it) containing an illuminating fiber bundle, a central image fiber and irrigating and vacuum channels. The bundle, fibers and channels are secured near the tube distal end by epoxy filler and insertion of the endoscope is through a catheter.
U.S. Pat. No. 4,850,359 (Putz) discloses what has come to be known as a depth electrode for monitoring electrical activity in the brain. Electrode placement to a depth in the brain is by using X-ray, magnetic resonance imaging (MRI) or the like.
A paper titled "Intraoperative Neurophysiology of the Corticospinal Tract" by V. Deletis and K. Kothbauer, published by Institute of Neurology and Neurosurgery, Beth Israel Medical Center North Division, New York, N.Y. mentions using electrodes for transcranial electrical stimulation and for recording D-waves from the spinal epidural or subdural space. The paper describes where and how electrodes are inserted and is incorporated herein by reference.
A feature of the trocar disclosed in the Hassler, Jr. patent is that it is rigid. The neuro endoscope disclosed in the Cohen et al. patent is also apparently rigid since it uses a stainless steel tube. While rigidity is undoubtedly needed in a surgical cutting tool or neuro endoscope of the described types, rigidity is a disadvantage in a device which must be temporarily implanted at a very-hard-to-reach site in the human body. And neither the Hassler, Jr. trocar nor the Cohen et al. endoscope is described as being suitable for electrical monitoring or stimulation.
An electrical monitoring apparatus which may be visually positioned and which is suitably small and flexible for use in very-hard-to-reach body sites would be an important advance in the art.